Friction rope



July 1, 1930.

R. S. O. LAWSON FRICTION ROPE Filed Sept. 26, 1929 w/r/vessfs gm 5; M

INVENTOR Patented July 1, 1939 ass.

ROBERT S. O. LAW'SON, OF JERSEY CITY, NEW JERSEY FRICTION BGPE Application filed September 26, 1829." SerialNo. 3%,338.

My invention relates to av specially constructed friction and tension rope.

The rope disclosed in my invention is especially adapted to be used in connection with i the let-oil motions of weaving looms and knitting machines.

In such machinery a taking-up and let-off motion act in conjunction to draw the warps forward at a suitable rate and tension. The

take-up=1notion of the machine is controlled by a positive ratchet gear which determines the rate'with which the warp is drawn forward by the take-uproll while the let-oh motion is controlled by a counter weightec friction rope wrapped around the brake pulley of the let-off roll, the friction of which determines the warp tension.

The uniformity of weave is entirely (.2- pendent on the amount of friction existing between the rope and the pulley whi h latter is generally known as the beam ruffle.

The friction between any length of rope.

and the ruiile 18 greater near the tight side of the rope and gradually decreases. around the ruffle towards the slack side, and thetension at the slack side of the rope will equal the difference between the tension at the tight side and the friction.

The rope friction however varies with the warp tension during the opening and the closing of the yarn shed which occurs for each cross-thread or pick inserted in the warp by the shuttle. e

When the yarn shed is closed the warpis slack and the tension of the rope at the tight end, which is the counter weight supported by the rope at this end, equals the tension at the slack end of the rope. I

hen the yarn shed is opened the warp tension increases and the tension in the rope at the slack end also decreases until a point is reached at which the rope will slip around the pulley.

the yarn shed the let-oil roll is turned through a considerable angle. Due to the elastic property of a fiber-rope this only results in slip at the end of the motion. then as the shed closes and the warp tension decreases the let- In )lain weavin during the o )enin of off roll turns back taking up the slack and keeps the warp tight.

- The more the rope is wrapped around the beam ruffle, the greater will the angle be through which the beam is turned without slippage, and it has been found necessary to wind the rope from three and a half to four and a half turns around the ruffle in order to prevent slippage. j 7

Where so many turns around the ruiile are employed the are of contact between the rope-and the rufiie becomes so great that an vexcessive friction will occur, and it is either necessary to employ lubricating means or to reduce the number of rope wraps around the ,ruflle, in which latter case special warp tensioners mustbeemployed.

Even dry lubricants like graphite and chalk are liable to soil the fabric and also their abrasive action on the rope shortens the life thereof.

I have discovered that when the surface of a rope is made to comprise a plurality 0t helically wound rope elements or strands of",

which one ormore have the outside diameter of the helix larger than the remaining ones, such a ropelmay be wrapped around theruitle the requirednumoer of turns without giving rise to an excessive friction.

ln the drawing I v I g Figure 1 is a cross section of a three strand rope of my construction.

Figure 2 is a short length of the three strand rope showing the strand arrangement vthereof.

outside diameterA of the' strand 2is larger than the outside diameter 13 of the strandsv 7 drawing denoted as D.

after my construction is Wrapped around the beam ruffle only the large surface strands are in contact with the ruffle and thearc of contact between the rope and the rufile will Figuresgand' d show the construction of a four strand rope 5.

This rope comprises fourstrands, which are twisted together and the outside diameter of the strands 6{and 7 on the drawing denoted as O is greater than that'of the helices de-1 V scribed by the smaller strands 8 and 9 on the It is to he understood that when a rope be materially reduced.

The tension of the Warp is'regulated by the frictionhet-Ween the rop'e'and the beam i'iiflle, and this friction depends on thecounter wight supported by the ro e-on the coefficient of'frictionhetween the rope and the rufiieyandon the are ofcontact between the I As the are of contact is practically out in half, in a rope of my construction it is pos sible to wrap around therufiie a rope having 7 a length"approximately double that of the conventional rope Without setting up an undue friction and the angle through which the let-oil? roll-Will turn as the rope stretches I through the opening oftlie yarn shed withr out slippage Willh'e approximately doubled.

It is alsoto henoted that in-a rope of my construction the Wear of the rope {will be conlined to only the larger rope strand elements, w While the remaining ones :Will remain unw0rnand of unimpaired strength.

. 7 It isalso to'be understood that by making each of the strands out ofa" number of relatively hard twisted yarns the Wearing quality 1 ofth e' strands becomes greater than if each of-the strands Werecomposed of one single large yarn. 7 ,With my construction only the surface yarnsof each strand are in contact with the ruffle whilethe inner yarns thereof are'protected and of'uni npaired strength.

r lo notwish tobe u'nderstoodas limiting myself to the specific details of construction as ithis manifest that variations and modifications maybe madein the adapation of the device to ..variousfconditions without departing from the spiritand scope of myinvent-ion. Iclaimk 1' A fiber ropecomprising a plurality of helicalsurfacestrands;each of said strands com posed oi: a plurality of yarns andlthe outside diameter of thehellx of a number of said.-

strands being larger-than the diameter ofthe remaining ones' j P j O. LAWZSO'N 

